Molded plastic elbow

ABSTRACT

An improved molded plastic elbow and a related mold assembly and manufacturing method are provided, wherein the elbow defines an internal flow path having a smoothly radiused inside turn. The elbow is formed by injecting plastic material into a tubular mold cavity formed by closed mold members in cooperation with a pair of slidably retractable core units of circular cross section and having distal ends in mating, angularly set end-to-end contact to form the internal flow path having a turn formed along the length thereof. Each core unit comprises an outer core pin to form an outer portion of the flow path and including a ramped track for slide-fit mounting of an inner slide segment which forms an inner portion of the flow path and further includes a curved inside edge to form a portion of the smoothly radiused inside turn. Initial retraction of each outer core pin from the mold cavity permits relative advancement of the inner slide segment along the ramped track toward a centerline of the flow path, sufficiently for the curved inside edge of the inner slide segment to clear the radiused inside turn of the molded elbow and thereby enable interference-free linear withdrawal of the core unit from the molded plastic part.

This is a divisional of U.S. application Ser. No. 09/487,153, filed Jan.19, 2000.

BACKGROUND OF THE INVENTION

This invention relates generally to improvements in molded plastic pipecomponents of the type typically found in irrigation sprinkler systemsand the like. More specifically, this invention relates to an improvedmolded plastic elbow and to a related mold assembly and method forproducing the elbow with an internal flow path defining a turn, whereinthe inside edge of the turn is smoothly radiused for reduced hydraulicpressure loss and to provide the elbow with improved fatigue resistance.

Plastic pipe and related molded plastic pipe fittings are well known inthe art for use in a variety of relatively low to mid-range fluidpressure applications, particularly such as in irrigation sprinklersystems to deliver irrigation water under pressure to sprinkler deviceshaving appropriate spray nozzles or the like to distribute the waterover a prescribed terrain area. In this regard, molded plastic pipefittings such as elbow fittings and the like are used forinterconnecting lengths of pipe at an angle, whereby such elbow fittingsdefine an internal flow path extending through a tum, typically a 90°turn. In one common form used primarily to interconnect elongated pipesections in an irrigation supply network, the elbow fitting is adaptedfor slip-fit adhesive connection to elongated pipe sections. In anothercommon form, the elbow fitting may include one or more threaded segmentsto form a so-called swing joint or coupling for quick and easy threadedconnection to adjacent pipe sections such as a riser pipe having asprinkler device mounted at an upper end thereof.

In the past, molded plastic elbow fittings have been formed by injectionmolding processes wherein plastic material is injected under heat andpressure into a mold cavity defined by closed mold members. A pair ofretractable core units are typically mounted to extend into the moldcavity in an angularly intersecting relation for cooperatively definingthe internal flow path through the injection molded fitting, whereinthese core units are adapted for sliding linear retraction from themolded part when the mold members are opened to release the molded part.Unfortunately, this standard molding apparatus and related process hasnecessarily limited the inside edge geometry of the internal flow pathto a relatively sharp corner in order to permit interference-free linearretraction of the sliding core units from the molded part. Thissharp-cornered geometry undesirably contributes to substantial hydraulicpressure loss as water flows through the elbow fitting. As a result,especially in an irrigation network including a substantial number ofsuch elbow fittings, the cumulative pressure loss attributable to theelbow fittings can adversely restrict the terrain area which can beeffectively irrigated. Moreover, the relatively sharp inside edgegeometry represents a stress concentration site which is susceptible tofatigue cracking in response to on-off pressure cycling over a period oftime.

Similarly, hydraulic pressure losses and fatigue problems have beennoted in other molded plastic elbow-type fluid conduits, such as, forexample, in the inlet and outlet portions of molded plastic valve bodiessuch as typical anti-syphon and pressure and flow regulating irrigationcontrol valves. In these instances, the valve bodies are typicallymolded with elbow-shaped inlet and outlet conduit sections for slip-fitadhesive or threaded connections to elongated supply pipes, and like theelbow fittings just discussed, the elbow sections function to direct theincoming and outlet fluid flows through turns of typically 90° withinthe valve body.

There exists, therefore, a significant need for an improved moldedplastic elbow and a related mold assembly and production method, whereinthe elbow has an internal flow path defining a turn with a smoothlycurved or smoothly radiused inside edge geometry, for reduced hydraulicpressure loss and improved fatigue resistance. The present inventionfulfills these needs and provides further related advantages.

SUMMARY OF THE INVENTION

In accordance with the invention, an improved molded plastic elbow andrelated mold assembly and production method are provided, wherein theelbow has an internal flow path defining a turn with a smoothly radiusedinside surface. The elbow is formed by injecting plastic material into amold cavity formed by closed mold members in cooperation with a pair ofslidably retractable core units having distal ends in mating andangularly set end-to-end engagement to form the internal flow path. Eachcore unit comprises an outer core pin slidably supporting an inner slidesegment on a ramped track, wherein the inner slide segment defines acurved inside edge to form a portion of the smoothly radiused insideturn in the molded part. Initial retraction of the outer core pin ofeach core unit from the mold cavity permits relative displacement of theassociated inner slide segment along the ramped track in a directiontoward a centerline of the flow path, sufficiently to clear the radiusedinside turn in the molded part and thereby permit interference-freelinear sliding retraction of the core unit from the molded plastic part.

The retractable core units cooperatively form the internal flow path tohave a generally circular cross sectional shape with a smoothly curvedoutside turn and additionally including the smoothly radiused insidetum. The outer core pins of the pair two core units include contourednose or distal ends each shaped to define a portion of the smoothlycurved outside turn, and further include planar abutment faces set at anangle for flush end-to-end engagement upon full advancement of the twocore units into the mold cavity. From its distal end, each outer corepin extends longitudinally with a part circular cross sectional shape toform an outer portion of the flow path. Importantly, an inner surface ofeach part circular core pin defines the ramped track extending on anangle longitudinally rearwardly and inwardly from the distal end to aradially extending stop surface formed generally at an associated end ofthe mold cavity.

The inner slide segment for each core unit has a part circular crosssectional shape and includes a ramped outer slide surface keyed forlongitudinal sliding movement on the ramped track of the associatedouter core pin. Actuator means are provided for controlling and limitingdisplacement of the inner slide segment along the ramped track between aretracted position nested on the outer core pin and cooperatingtherewith to define an inner portion of the internal flow path, and anadvanced position protruding longitudinally beyond the distal end of theouter core pin. The distal ends of the inner slide segments also includeplanar abutment faces set at an angle for flush end-to-end engagement,substantially coplanar with the distal end abutment faces of the outercore pins upon full advancement of the two core units into the moldcavity. The inner slide segments additionally include the curved insideedges disposed generally at the distal ends thereof for cooperativelyforming the smoothly radiused inner turn.

When the outer core pin of each core unit is retracted from the moldcavity, following injection forming of the molded elbow therein, theactuator means associated with each inner slide segment accommodatesadvancing or forward relative displacement of the inner slide segmentalong the ramped track. Such advancing displacement is accompanied by anoutward shift in the position of the inner slide segment in a directiontoward the centerline of the flow path in the molded part. This outwardshift by the inner slide segment carries the curved inside edge thereofto a position spaced slightly from the curved inside turn of the flowpath formed in the molded part, so that the entire core unit can belongitudinally and linearly retracted from the molded part withoutinterference.

Other features and advantages of the invention will become more apparentfrom the following detailed description, taken in conjunction with theaccompanying drawings which illustrate, by way of example, theprinciples of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings illustrate the invention. In such drawings:

FIG. 1 is a perspective view of a molded plastic elbow, herein a plasticelbow fitting, constructed in accordance with the invention;

FIG. 2 is a vertical sectional view taken generally on the line 2—2 ofFIG. 1;

FIG. 3 is a fragmented and somewhat schematic vertical sectional view ofa mold assembly, illustrating closed mold members cooperating with apair of retractable core units to define a mold cavity for injectionmolding of the elbow fitting of FIGS. 1 and 2;

FIG. 4 is a fragmented sectional view of the mold assembly similar toFIG. 3, but showing the elbow fitting formed within the mold cavity;

FIG. 5 is a fragmented sectional view of the mold assembly similar toFIG. 4, and showing initial retraction of one of the core units from themold assembly;

FIG. 6 is a fragmented sectional view of the mold assembly similar toFIG. 5, and illustrating retraction of both of the core units from themold assembly;

FIG. 7 is an exploded perspective view depicting assembly of the a corepin and a related inner slide segment forming each of the retractablecore units;

FIG. 8 is a perspective view illustrating the distal end and an upper orradially inner side of one of the inner slide segments shown in FIG. 7;

FIG. 9 is a perspective view showing the proximal end and a lower orradially outer side of the inner slide segment of FIG. 8;

FIG. 10 is a perspective view depicting the distal end and a lower orradially outer side of one of the core pins shown in FIG. 7; and

FIG. 11 is a perspective view showing the proximal end and an upper orradially inner side of the core pin of FIG. 10.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

As shown in the exemplary drawings, the present invention relates to animproved molded plastic elbow, in this instance a new and improvedmolded plastic elbow fitting referred to generally in the accompanyingdrawings by the reference numeral 10, and a related molding assembly andmethod for producing the improved elbow and fitting. As shown in FIGS. 1and 2, the elbow fitting 10 comprises a unitary or one-piece tubularelement formed from molded plastic to define an internal flow path 12(FIG. 2) having a turn formed along the length thereof. The elbowfitting 10 comprises a plumbing connector for coupling fluid flow suchas water or the like between a pair of pipes 14 (shown in dotted linesin FIGS. 1 and 2)

The improved elbow fitting 10 of the present invention is particularlydesigned to form the internal flow path 12 with a smoothly radiusedinside turn, as identified by reference numeral 16 in FIG. 2. In thisregard, molded plastic elbow fittings of this general type are commonlyused in relatively low to midrange fluid pressure applications,particularly such as irrigation sprinkler systems to deliver irrigationwater under pressure to sprinkler devices which distribute the waterover a prescribed terrain area. Molded plastic pipe fittings such as theillustrative elbow fitting 10 and the like are used for interconnectinglengths of pipe 14 at an angle, whereby such elbow fittings define theinternal flow path 12 extending through a turn, typically a 90° turn asshown in FIG. 2. However, according to prior injection moldingtechniques, the internal flow path through the elbow fitting has beenformed by linearly advancing and retracting an intersecting pair ofsliding cores into a mold cavity, resulting in forming the flow pathwith a relatively sharp edge or corner at the inside turn. Thesharp-cornered inside turn geometry results in a substantial hydraulicpressure loss during normal use, and additionally represents a stressconcentration site susceptible to fatigue cracking and failure. Theimproved elbow fitting 10 of the present invention, including thesmoothly radiused inside turn 16, overcomes these problems anddisadvantages.

FIGS. 3–11 illustrate the improved molding assembly and method of thepresent invention for making the improved elbow fitting 10. In general,a pair of mold members 18 and 20 designed for use in a standardinjection molding machine (not shown) are movable to a closed positiondefining a mold cavity 22 (FIG. 3) having a size and shape conforming tothe exterior geometry of the elbow fitting 10 to be molded. A pair ofslidably retractable core units 24 are advancible into the mold cavity22 to define the geometry of the internal flow path 12 to be molded intothe elbow fitting. Importantly, each sliding unit 24 comprises an outercore pin 26 shaped to form an outer portion of the flow path 12, and aninner slide segment 28 shaped to form an inner portion of the flow path12. Each inner slide segment 28 includes a curved inside edge ortrigger-shaped portion 30 formed generally adjacent a distal endthereof, to extend or wrap partially around the smoothly radiused insideturn to be formed in the molded part. The inner slide segment 28 isadapted for sliding displacement on the outer core pin 26, uponretraction of the core unit 24 from the molded part, to permit anoutward shift in the position of the curved inside edge 30 sufficientlyto accommodate interference-free withdrawal of the entire sliding coreunit 24 from the molded part.

More specifically, FIG. 3 illustrates the pair of mold members 18, 20advanced in the direction of arrows 32 toward a normally closed positiondefining the elbow shaped mold cavity 22. As shown, the two core units24 are adapted for advancement by means of suitable primary actuators 33in the direction of arrows 34 to protrude from different directions intothe mold cavity 22, with distal ends of the two core units 24 setangularly for end-to-end abutting contact generally at a mid point ofthe turn to be molded along the flow path 12 of the elbow fitting. Inthis regard, the illustrative drawings show the distal ends of thesliding core units 24 set at an angle of about 45°, to form anapproximate 90° turn along the flow path. It will be recognized andunderstood, however, that alternative elbow fitting configurationshaving flow path turns of different angular magnitudes may be formedaccording to the invention.

Each core unit 24 comprises the outer core pin 26 having a part circularcross sectional shape (FIGS. 3, 7 and 10–11) for advancement into themold cavity 22. This part circular core pin 26 protrudes from the end ofa solid core pin base 36 of circular cross section adapted for suitableconnection as by a control rod 37 to the associated primary actuator 33for linearly advancing and retracting the core pin 26 relative to themold cavity 22. The arcuate exterior surface of the part circular corepin 26 defines an outer portion of the flow path 12, and includes aninwardly curved and smoothly contoured nose end 38 shaped to formone-half of a smoothly radiused outside turn 42 (FIG. 2) to be formedalong the flow path 12 within the molded part. The contoured nose end 38merges with a distal end face 40 (shown best in FIGS. 7 and 11)comprising a planar abutment face extending angularly rearwardly andinwardly therefrom, set at an angle of about 45° to bisect the turn inthe flow path 12, as previously described. From an inner margin of thedistal end face 40, an elongated ramped track 44 (FIGS. 7 and 11) isformed on an inner surface of the outer core pin 26 to extend rearwardlyand inwardly relative to a longitudinal centerline of the sliding coreunit 24 and the associated flow path 12 to be formed, terminatinggenerally at the associated end of the mold cavity 22 in a radiallyextending stop surface 46 located at a distal end of the core pin base36. While the specific geometry of the ramped track 44 may vary, FIGS.3–7 show the ramped track 44 extending generally from the distal endface 40 at a point disposed outboard of an axial centerline of the coreunit 24, rearwardly and inwardly at an angle of about 15°–20° to a pointdisposed inboard of the axial centerline before terminating at the stopsurface 46. In a fully advanced position as viewed in FIG. 3, the distalend faces 40 of the two core pins 26 are disposed in end-to-end abuttingcontact so that the outer core pins 26 of the two sliding core unitscontinuously define the shape of the outer portion of the flow path 12,including the smoothly radiused outside turn 42. If desired, as shown inFIG. 7, one of the core pins 26 may include a short alignment tab 45protruding from the distal end face 40 thereof, for mated and seatedreception into a shallow detent 47 formed in the distal end face 40 ofthe other core pin 26, for interlocking engagement of the two core pins26 in the fully advanced position (FIGS. 3 and 4).

The inner slide segment 28 of each retractable core unit 24 is slidablycarried on the ramped track 44 of the associated outer core pin 26. Asshown in FIGS. 3 and 7–9, each inner slide segment 28 also has a partcircular cross sectional shape for nested and mating reception in aretracted position on the ramped track 44 with a proximal end 50engaging the stop surface 46. In this position, the inner slide segment28 cooperates with the associated outer core pin 26 to define a fullcircle cross section for the flow path 12 to be molded into the elbowfitting 10. More specifically, the inner slide segment 28 includes anangularly set outer slide surface 52 extending from the proximal end 50to a distal end face 54 which is angularly set to define a planarabutment face to engage and contact the distal end face 54 of the innerslide segment 28 on the other sliding core unit 24, when the slidingcore units 24 are fully advanced into the mold cavity. FIG. 3 shows thedistal end faces 54 of the two inner slide segments 28 in end-to-endengagement, and disposed at the mid point of the flow path turn in aposition substantially coplanar with the abutted distal end faces 40 ofthe outer core pins 26. An elongated depending key 53 such as a dovetailkey (FIGS. 7–9) protrudes outwardly from the outer slide surface 52 ofthe inner slide segment 28 for longitudinal sliding reception within aslot 55 such as dovetail slot (FIGS. 7 and 11) formed in the rampedtrack 44 of the associated outer core pin 26. A control rod 56 isconnected to the rear or proximal end 50 of the inner slide segment 28and extends rearwardly therefrom through a guide port 57 formed in thecore pin base 36 to the exterior of the mold cavity 22. This control rod56 accommodates sliding displacement of the inner slide segment 28 alongthe ramped track 44 on the outer core pin 26, while preventing the innerslide segment 28 from sufficient advancing displacement to separate fromthe outer core pin 26.

In accordance with one primary aspect of the invention, each inner slidesegment 28 additionally includes the curved inside edge ortrigger-shaped portion 30 at a position adjacent the distal end face 54thereof. This curved inside edge 30 defines a continuation of the flowpath 12 of circular cross section, extending or wrapping part-waythrough the turn, and cooperates with the curved inside edge 30 of theother inner slide segment 28 to form the smoothly radiused inside turn16. As a result, the curved inside edges 30 of the two inner slidesegments 28 necessarily protrude inwardly beyond an innermost surface ofthe associated linear segment of the flow path 12 leading to the turn.Accordingly, the curved inside edge 30 of each inner slide segment 28must be displaced outwardly toward a centerline of the associatedsliding core unit and toward a centerline of the flow path 12 formed inthe molded part, before the sliding core unit 24 can be retracted andwithdrawn from the molded part.

FIG. 3 additionally shows a pair of insert sleeves 58 carried slidablyabout the two core units 24, respectively, for advancement a shortdistance into the opposite ends of the mold cavity 22. The illustrativeinsert sleeves 58 have a smooth-surfaced configuration to form shortcounterbores 59 (FIG. 2) in the opposite ends of the molded elbowfitting 10, wherein these counterbores 59 comprise slip-fit femaleconnectors for connection by an adhesive or the like to the ends of thefluid-carrying pipes 14 (FIGS. 1 and 2), all in a manner well known topersons having ordinary skill in the art. Alternately, it will berecognized and understood that the insert sleeves 58 may be configuredto form threaded female connectors for thread-in coupling with theassociated pipes 14, or alternately adapted to form slip-fit male orthreaded male connectors, or any combination thereof.

FIG. 4 shows the mold apparatus of FIG. 3, with plastic materialinjected through an illustrative sprue 60 to form the molded part. Theouter core pin 26 of each core unit 24 can be retracted or withdrawnfrom the molded elbow fitting 10. FIG. 5 illustrates initial retractionor withdrawal of one of the outer core pins 26, by appropriate operationof the primary actuator 33, wherein such retraction is accompanied byrelative advancement of the associated inner slide segment 28 downwardlyand forwardly along the ramped track 44. In this regard, suchadvancement of the inner slide segment 28 can occur by positiveadvancement of the associated control rod 56 in response to operation ofa secondary actuator 64 connected thereto. Alternately, such relativeadvancement can occur as a result of the curved inside edge 30physically catching on the inside turn of the molded part to provide asufficient resistance force preventing concurrent linear retraction ofthe inner slide segment 28. Instead, the inner slide segment 28 isforced to translate along the ramped track 44 relative to the retractingouter core pin 26, for outward positional shifting of the inner slidesegment 28 sufficient for the inside curved edge 30 to clear the insideturn of the molded part. In either case, the control rod 56 couples theinner slide segment 28 to the associated core pin 26 is a mannerpreventing the inner slide segment from translating off the distal endof the core pin. As soon as the inner slide segment 28 is shiftedoutwardly a sufficient distance toward the centerline of the core unit24 and the related flow path formed in the molded part, the entire coreunit 24 can be retracted from the mold assembly without interference.FIG. 6 shows linear retraction of both core units 24, with the innerslide segments 28 of each sliding core unit advanced along theassociated ramped tracks for shift outwardly relative to the inside turn16 of the molded part to permit interference-free withdrawal of the coreunits 24 therefrom. The mold members 18, 20 can then be opened torelease the finished molded plastic elbow fitting 10.

The resultant molded elbow fitting 10 is thus formed with the continuousflow path 12 having the smoothly radiused inside turn 16. During use,this flow path geometry achieves a substantial reduction in pressuredrop through the elbow fitting, in comparison with a standard flow pathgeometry including a relatively sharp corner or edge at the inside turn.Moreover, by providing the smoothly contoured inside turn in lieu of asharp-cornered inside turn, a stress concentration site whereat fatiguefailure in response to on-off pressure cycling can otherwise occur isalso eliminated from the molded part.

From the foregoing, it should be appreciated that the mold assembly andmethod of the present invention although illustrated and described inconnection with the formation of a new and improved molded plastic elbowfitting 10, could also be utilized with the production of other moldedplastic parts wherein an elbow-shaped flow path is desired. For example,a person skilled in the art would recognize that the mold assembly andmethod of the present invention could be readily used to produce theelbow-shaped flow-paths found in typical molded plastic valve bodiessuch as anti-siphon and fluid pressure and flow control irrigationvalves. In such valves, it is common to use a 90° elbow-shaped inletand/or outlet passageway through which the valve is connected toadjacent supply pipes, the elbow-shaped passageway typically havingheretofore been formed using conventional intersecting cores similar tothose described herein above in connection with the molding of prior artplastic elbow fittings. Through use of the mold assembly and method ofthe present invention, a valve body shaped according to the moldedplastic part shown in FIGS. 1 and 2, or otherwise modified in geometryand/or adapted for assembly with other valve housing components (notshown), is provided with in internal flow path having elbow-shaped inletand/or outlet passageways formed with a smoothly radiused inside turnsurface geometry to provide reduced pressure losses and improved fatigueresistence.

A variety of further modifications and improvements in and to theimproved molded plastic elbow and related method and apparatus for theproduction thereof will be apparent to those persons skilled in the art.In this regard, while the invention has been shown and described withrespect to a single cavity mold apparatus, persons skilled in the artwill understand and appreciate that a multiple cavity mold assembly maybe employed. Moreover, it will be appreciated that other types ofdevices may be formed with internal flow paths defined by smoothlyradiused inside turns, the essential requirement being that the elbowpassageway be accessible during the molding process from both ends.Accordingly, no limitation on the invention is intended by way of theforegoing description and accompanying drawings, except as set forth inthe appended claims.

1. A mold assembly for making a molded plastic body having anelbow-shaped internal flow path defined by a smoothly radiused insideturn surface, said mold assembly comprising: a pair of mold membersadapted for movement to a closed position to define a mold cavity havinga shape conforming to the exterior geometry of a body to be molded; anda pair of retractable core units each movable between an advancedposition protruding into said mold cavity and cooperating with eachother to define an internal flow path in the body to be molded, and aretracted position substantially withdrawn from said mold cavity; saidcore units having angularly set distal end faces for abutting end-to-endengagement with each other when said core units are ins aid advancedpositions to define the internal flow path with a turn formed along thelength thereof; each of said core units comprising an outer core pindefining an outer portion of the internal flow path and including aramped track extending longitudinally and angularly inwardly from adistal end thereof, and an inner slide segment defining an inner portionof the internal flow path, said inner slide segment being movablycarried on said ramped track and including a curved inner edge disposedgenerally at a distal end thereof, wherein said curved inner edges ofsaid inner slide segments of said core units cooperatively define asmoothly radiused inside turn surface of the internal flow path; saidinner slide segment of each of said core units being movable along saidramped track on the associated outer core pin upon movement of said coreunit toward said retracted position subsequent to molding of said bodywithin said mold cavity to shift said inner slide segment in an outwarddirection relative to a centerline of the internal flow pathsufficiently for interference-free withdrawal of said core unit fromsaid mold cavity and said body molded therein.
 2. The mold assembly ofclaim 1 wherein said core units cooperatively define the internal flowpath to have a generally circular cross-section shape.
 3. The moldassembly of claim 1 further including insert means cooperating with saidmold members to form connection means on the body to be molded forinterconnecting the body to a pair of pipes.
 4. The mold assembly ofclaim 1 wherein the turn formed along the length of the internal flowpath comprises a turn of about 90°.
 5. The mold assembly of claim 1wherein the mold members form a generally elbow shape.
 6. The moldassembly of claim 1 wherein said angularly set distal end faces on saidcore units comprise angularly set distal end faces on the distal ends ofsaid outer core pins for abutting end-to-end engagement with each otherwhen said core units are in said advanced positions, and angularly setdistal end faces on the distal ends of said inner slide segments forabutting end-to-end engagement with each other when said core units arein said advanced positions, said core pins and said inner slide segmentscooperatively defining the internal flow path with the turn formed alongthe length thereof when said core units are in said advanced positions.7. The mold assembly of claim 1 further including interlocking means onsaid distal end faces of said core pins for interlocking said core pinswhen said distal end faces are in abutting end-to-end engagement.
 8. Themold assembly of claim 1 further including interengaging key and slotmeans formed on said outer core pin and said inner slide segment of eachof said core units, for slidably guiding said inner slide segment alongsaid ramped track.
 9. The mold assembly of claim 7 further includingmeans for limiting displacement of said inner slide segment along saidramped track to prevent separation of said inner slide segment from saidouter core pin.